I've not got one, so I don't know for sure but I've been told that with most cars with "stop/start" you can turn it off. And in the case of a car getting umpty with a queue and stopping and starting, any good driver surely would.

Its a gimic in my book that enables manufacturer's to get better EU CO and fuel consumption figures than can normally be obtained.

Quite. Whoever thought that that taxing a car on its theoretical fuel consumption (as opposed to its actual consumption via fuel duty) is a moron.

It works in the NEDC because about a third of the cycle is spent idling. A little 4 pot diesel can idle for over 8 hours on a single gallon of fuel-that's a lot of idling for not a lot of fuel.

...and when warm, and high drain electrical items are switched off, the idle consumption is pretty low anyway. For long stops, the ignition key works as a perfectly good start-stop system.

In our office a couple of the engineers have Volvo V50's as company cars. Both are identical 1.6D Eco models but one has stop start fitted. Not 100% sure why but I think they were the cars the leasing company could get within the time frame. The non stop/start car has an EU combined of 62.8 mpg, £30 VED, 119 CO's and 13% BIK, the stop/start one has an EU combined of 72.3 mpg, £20 VED, 104 CO's and 13% BIK (think this is due to change over the next couple of years). Our company policy is to reimburse users for fuel purchased based on business mileage covered and the EU combined figure but if users can prove they are not getting that mpg they can appeal and get it modified, because of this all users keep a careful log of mileage and fuel bought. Both cars get virtually the same type of use (3 or more long motorway runs a week) and both cars do virtually the same mpg, from memory its about 52mpg. The user of the stop/start car had huge difficulty getting the finance director to accept that his supposedly much more economical car was only doing the same mpg as the standard one and getting his fuel rate adjusted.